Legally, because the Board failed to live up to its contract obligations by not giving an already agreed to raise, the union has the right to terminate the current contract, if it so desires.

That will be decided later Tuesday in a vote by its house of delegates.

The Sun-Times reports reopening the current contract could pave the way for a strike, but could also make it easier for Mayor Rahm Emanuel to impose his long-stated goal of lengthening the school day and school year.

The Teachers Union has warned previously that a strike could be a consequence of the vote to cancel the pay raise.

In June, union president Karen Lewis said: “It very well could (lead to a strike), but the operative word here is ‘could.’ That would be the will of the membership.”

The last teachers’ strike was in the fall of 1987 when Harold Washington was mayor, and lasted four weeks. It was similarly prompted by the denial of a pay raise the Chicago Board of Education said it couldn’t afford, according to past published reports.

Teachers have gotten contractual 4 percent pay hikes the past four years. Administrators and other non-union employees haven’t seen raises in two years, and were forced to take as many as 15 unpaid furlough days this year.